feat(distribution): 公告中心支持分站自定义

公告中心（前台公告列表/详情）此前完全没有站点概念，分站访客只能看到主站公告。
本次按「默认继承主站、站长可切仅本站」的口径支持分站自定义。

数据与口径：
- 新增 announcements.distribution_site_id（0=主站），前台按站点隔离
- 新增 distribution_sites.announcement_mode：inherit（默认，主站+本站）/ own_only（仅本站）

后端：
- 公告模块新增 ResolvePublicSiteScope：主站 [0]、inherit [0, siteID]、own_only [siteID]，
  站点编码无效/已停用回落主站；列表与详情都按该范围过滤，详情不再允许跨站按 ID 读取
- 管理端公告列表支持按站点筛选（site_id：不传=全部，0=主站，>0=分站）并带出站点名
- 分销模块新增本站公告 CRUD（distribution/announcement.go）：强制 distribution_site_id=本站，
  先过 ensureSiteAccess，跨站更新/删除/上下架一律 ErrAnnouncementNotFound
- UpdateSiteBranding 支持 announcement_mode 切换（非法值报错，读侧非法历史值回落 inherit）
- 新增权限 distribution:announcement_view|manage 并授予 super_admin/ops/finance，
  站长开通时继承 ops 角色即自动获得
- 路由：站长侧 /api/distribution/announcements*，平台侧 /api/admin/distribution/announcements*

前端：
- 分销后台新增「公告中心」页：来源开关（继承主站+本站 / 仅本站）、本站公告列表与
  新建/编辑/发布/下架/归档/恢复/删除，空态按来源模式给出引导
- 平台后台公告页新增「站点」列与筛选，新建公告可选择归属站点（主站或指定分站代发）
- 前台 PC/移动无需改动：请求已带 X-Distribution-Site-Code，后端按站点隔离，页面已有空态

测试：
- 公告模块：主站/继承/仅本站三种可见范围、跨站详情拦截、无效站点回落、管理端站点筛选
- 分销模块：本站公告 CRUD 与跨站防护、公告来源开关校验与非法值容错

backend/internal/modules/distribution/announcement.go

@@ -0,0 +1,235 @@
+package distribution
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"time"
+
+	"hfb_sys/backend/internal/model"
+
+	"gorm.io/gorm"
+)
+
+// 分站公告中心：站长在分销后台自助维护本站公告。
+//
+// 站点隔离口径：所有写操作与列表查询都强制 distribution_site_id = siteID，
+// 且先通过 ensureSiteAccess 校验当前管理员对该站点的访问权，避免跨站读写。
+// 前台展示范围由站点 announcement_mode 决定（见 announcement 模块 ResolvePublicSiteScope）。
+
+// normalizeAnnouncementMode 校验公告中心来源模式，空值按默认 inherit 处理。
+func normalizeAnnouncementMode(value string) (string, error) {
+	switch strings.TrimSpace(value) {
+	case "", model.AnnouncementModeInherit:
+		return model.AnnouncementModeInherit, nil
+	case model.AnnouncementModeOwnOnly:
+		return model.AnnouncementModeOwnOnly, nil
+	default:
+		return "", ErrInvalidAnnouncementMode
+	}
+}
+
+// ListSiteAnnouncements 分页查询本站公告（含草稿/归档，供站长管理）。
+func (r *Repository) ListSiteAnnouncements(ctx context.Context, adminID, siteID uint64, status string, page, pageSize int) (*SiteAnnouncementPage, error) {
+	if siteID == 0 {
+		return nil, ErrSiteNotFound
+	}
+	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
+		return nil, err
+	}
+	if page < 1 {
+		page = 1
+	}
+	if pageSize < 1 {
+		pageSize = 20
+	}
+	if pageSize > 100 {
+		pageSize = 100
+	}
+
+	base := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("distribution_site_id = ?", siteID)
+	if s := strings.TrimSpace(status); s != "" {
+		base = base.Where("status = ?", s)
+	}
+
+	var total int64
+	if err := base.Session(&gorm.Session{}).Count(&total).Error; err != nil {
+		return nil, err
+	}
+
+	var rows []model.Announcement
+	if err := base.Session(&gorm.Session{}).
+		Order("is_pinned DESC, priority DESC, id DESC").
+		Offset((page - 1) * pageSize).
+		Limit(pageSize).
+		Find(&rows).Error; err != nil {
+		return nil, err
+	}
+
+	items := make([]SiteAnnouncementDTO, 0, len(rows))
+	for _, row := range rows {
+		items = append(items, toSiteAnnouncementDTO(row))
+	}
+	return &SiteAnnouncementPage{Items: items, Total: total, Page: page, PageSize: pageSize}, nil
+}
+
+// CreateSiteAnnouncement 在指定站点下新建公告（草稿）。
+func (r *Repository) CreateSiteAnnouncement(ctx context.Context, adminID, siteID uint64, req CreateSiteAnnouncementRequest) (*SiteAnnouncementDTO, error) {
+	if siteID == 0 {
+		return nil, ErrSiteNotFound
+	}
+	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
+		return nil, err
+	}
+	createdBy := adminID
+	row := model.Announcement{
+		DistributionSiteID: siteID,
+		Title:              strings.TrimSpace(req.Title),
+		Content:            req.Content,
+		Category:           strings.TrimSpace(req.Category),
+		Priority:           req.Priority,
+		IsPinned:           req.IsPinned,
+		IsImportant:        req.IsImportant,
+		Status:             "draft",
+		CreatedBy:          &createdBy,
+	}
+	if row.Category == "" {
+		row.Category = "notice"
+	}
+	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
+		return nil, err
+	}
+	dto := toSiteAnnouncementDTO(row)
+	return &dto, nil
+}
+
+// UpdateSiteAnnouncement 更新本站公告内容。
+func (r *Repository) UpdateSiteAnnouncement(ctx context.Context, adminID, siteID, id uint64, req UpdateSiteAnnouncementRequest) (*SiteAnnouncementDTO, error) {
+	if siteID == 0 {
+		return nil, ErrSiteNotFound
+	}
+	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
+		return nil, err
+	}
+	row, err := r.findSiteAnnouncement(ctx, siteID, id)
+	if err != nil {
+		return nil, err
+	}
+
+	updates := map[string]any{
+		"priority":     req.Priority,
+		"is_pinned":    req.IsPinned,
+		"is_important": req.IsImportant,
+	}
+	if title := strings.TrimSpace(req.Title); title != "" {
+		updates["title"] = title
+	}
+	if req.Content != "" {
+		updates["content"] = req.Content
+	}
+	if category := strings.TrimSpace(req.Category); category != "" {
+		updates["category"] = category
+	}
+	if err := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("id = ?", row.ID).Updates(updates).Error; err != nil {
+		return nil, err
+	}
+	updated, err := r.findSiteAnnouncement(ctx, siteID, id)
+	if err != nil {
+		return nil, err
+	}
+	dto := toSiteAnnouncementDTO(*updated)
+	return &dto, nil
+}
+
+// UpdateSiteAnnouncementStatus 站点公告上下架：publish=发布，archive=归档，unarchive=取消归档。
+func (r *Repository) UpdateSiteAnnouncementStatus(ctx context.Context, adminID, siteID, id uint64, action string) (*SiteAnnouncementDTO, error) {
+	if siteID == 0 {
+		return nil, ErrSiteNotFound
+	}
+	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
+		return nil, err
+	}
+	row, err := r.findSiteAnnouncement(ctx, siteID, id)
+	if err != nil {
+		return nil, err
+	}
+
+	now := time.Now()
+	updates := map[string]any{}
+	switch strings.TrimSpace(action) {
+	case "publish":
+		updates["status"] = "published"
+		updates["published_at"] = now
+	case "archive":
+		updates["status"] = "archived"
+	case "unarchive":
+		updates["status"] = "published"
+		updates["published_at"] = gorm.Expr("COALESCE(published_at, ?)", now)
+	default:
+		return nil, ErrInvalidListingStatus
+	}
+	if err := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("id = ?", row.ID).Updates(updates).Error; err != nil {
+		return nil, err
+	}
+	updated, err := r.findSiteAnnouncement(ctx, siteID, id)
+	if err != nil {
+		return nil, err
+	}
+	dto := toSiteAnnouncementDTO(*updated)
+	return &dto, nil
+}
+
+// DeleteSiteAnnouncement 删除本站公告。
+func (r *Repository) DeleteSiteAnnouncement(ctx context.Context, adminID, siteID, id uint64) error {
+	if siteID == 0 {
+		return ErrSiteNotFound
+	}
+	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
+		return err
+	}
+	row, err := r.findSiteAnnouncement(ctx, siteID, id)
+	if err != nil {
+		return err
+	}
+	return r.db.WithContext(ctx).Where("id = ?", row.ID).Delete(&model.Announcement{}).Error
+}
+
+// findSiteAnnouncement 按站点归属读取公告，跨站 ID 一律视为不存在。
+func (r *Repository) findSiteAnnouncement(ctx context.Context, siteID, id uint64) (*model.Announcement, error) {
+	var row model.Announcement
+	err := r.db.WithContext(ctx).Where("id = ? AND distribution_site_id = ?", id, siteID).First(&row).Error
+	if err != nil {
+		if errors.Is(err, gorm.ErrRecordNotFound) {
+			return nil, ErrAnnouncementNotFound
+		}
+		return nil, err
+	}
+	return &row, nil
+}
+
+func toSiteAnnouncementDTO(a model.Announcement) SiteAnnouncementDTO {
+	return SiteAnnouncementDTO{
+		ID:                 a.ID,
+		DistributionSiteID: a.DistributionSiteID,
+		Title:              a.Title,
+		Content:            a.Content,
+		Category:           a.Category,
+		Priority:           a.Priority,
+		IsPinned:           a.IsPinned,
+		IsImportant:        a.IsImportant,
+		ViewCount:          a.ViewCount,
+		Status:             a.Status,
+		PublishedAt:        a.PublishedAt,
+		CreatedAt:          a.CreatedAt,
+		UpdatedAt:          a.UpdatedAt,
+	}
+}
+
+// normalizeAnnouncementModeOrInherit 读侧容错：非法/历史空值一律按默认继承口径返回。
+func normalizeAnnouncementModeOrInherit(value string) string {
+	mode, err := normalizeAnnouncementMode(value)
+	if err != nil {
+		return model.AnnouncementModeInherit
+	}
+	return mode
+}

backend/internal/modules/distribution/announcement_test.go

@@ -0,0 +1,142 @@
+package distribution
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"hfb_sys/backend/internal/model"
+)
+
+// TestSiteAnnouncementCRUDIsSiteScoped 验证站长自助公告只能读写本站数据：
+// 列表/更新/删除/上下架都强制 distribution_site_id = 本站，跨站 ID 视为不存在。
+func TestSiteAnnouncementCRUDIsSiteScoped(t *testing.T) {
+	db := distributionTestDB(t)
+	repo := NewRepository(db)
+	ctx := context.Background()
+
+	siteA, err := repo.CreateSite(ctx, CreateSiteRequest{
+		SiteCode: "ann_site_a", SiteName: "公告站A", Domain: "ann-a.hfb.local",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	siteB, err := repo.CreateSite(ctx, CreateSiteRequest{
+		SiteCode: "ann_site_b", SiteName: "公告站B", Domain: "ann-b.hfb.local",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	created, err := repo.CreateSiteAnnouncement(ctx, 0, siteA.ID, CreateSiteAnnouncementRequest{
+		Title: "本站公告", Content: "内容", Category: "notice",
+	})
+	if err != nil {
+		t.Fatalf("CreateSiteAnnouncement failed: %v", err)
+	}
+	if created.DistributionSiteID != siteA.ID || created.Status != "draft" {
+		t.Fatalf("unexpected created announcement: %+v", created)
+	}
+
+	// 列表按站点隔离
+	pageA, err := repo.ListSiteAnnouncements(ctx, 0, siteA.ID, "", 1, 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if pageA.Total != 1 {
+		t.Fatalf("A 站应有 1 条公告, got %d", pageA.Total)
+	}
+	pageB, err := repo.ListSiteAnnouncements(ctx, 0, siteB.ID, "", 1, 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if pageB.Total != 0 {
+		t.Fatalf("B 站不应看到 A 站公告, got %d", pageB.Total)
+	}
+
+	// 跨站更新/删除/上下架一律拒绝
+	if _, err := repo.UpdateSiteAnnouncement(ctx, 0, siteB.ID, created.ID, UpdateSiteAnnouncementRequest{Title: "改"}); !errors.Is(err, ErrAnnouncementNotFound) {
+		t.Fatalf("跨站更新应返回 ErrAnnouncementNotFound, got %v", err)
+	}
+	if err := repo.DeleteSiteAnnouncement(ctx, 0, siteB.ID, created.ID); !errors.Is(err, ErrAnnouncementNotFound) {
+		t.Fatalf("跨站删除应返回 ErrAnnouncementNotFound, got %v", err)
+	}
+	if _, err := repo.UpdateSiteAnnouncementStatus(ctx, 0, siteB.ID, created.ID, "publish"); !errors.Is(err, ErrAnnouncementNotFound) {
+		t.Fatalf("跨站发布应返回 ErrAnnouncementNotFound, got %v", err)
+	}
+
+	// 本站更新与发布
+	updated, err := repo.UpdateSiteAnnouncement(ctx, 0, siteA.ID, created.ID, UpdateSiteAnnouncementRequest{
+		Title: "本站公告（改）", Content: "新内容", Category: "rule", Priority: 5, IsPinned: true,
+	})
+	if err != nil {
+		t.Fatalf("UpdateSiteAnnouncement failed: %v", err)
+	}
+	if updated.Title != "本站公告（改）" || updated.Category != "rule" || !updated.IsPinned || updated.Priority != 5 {
+		t.Fatalf("unexpected updated announcement: %+v", updated)
+	}
+	published, err := repo.UpdateSiteAnnouncementStatus(ctx, 0, siteA.ID, created.ID, "publish")
+	if err != nil {
+		t.Fatalf("publish failed: %v", err)
+	}
+	if published.Status != "published" || published.PublishedAt == nil {
+		t.Fatalf("发布后状态/时间不正确: %+v", published)
+	}
+	archived, err := repo.UpdateSiteAnnouncementStatus(ctx, 0, siteA.ID, created.ID, "archive")
+	if err != nil {
+		t.Fatalf("archive failed: %v", err)
+	}
+	if archived.Status != "archived" {
+		t.Fatalf("归档后状态不正确: %+v", archived)
+	}
+	if _, err := repo.ListSiteAnnouncements(ctx, 0, siteA.ID, "archived", 1, 20); err != nil {
+		t.Fatalf("按状态查询失败: %v", err)
+	}
+	if err := repo.DeleteSiteAnnouncement(ctx, 0, siteA.ID, created.ID); err != nil {
+		t.Fatalf("本站删除失败: %v", err)
+	}
+}
+
+// TestUpdateSiteBrandingAnnouncementMode 验证公告来源开关可保存并校验非法值。
+func TestUpdateSiteBrandingAnnouncementMode(t *testing.T) {
+	db := distributionTestDB(t)
+	repo := NewRepository(db)
+	ctx := context.Background()
+
+	site, err := repo.CreateSite(ctx, CreateSiteRequest{
+		SiteCode: "ann_mode_site", SiteName: "模式站", Domain: "ann-mode.hfb.local",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if site.AnnouncementMode != model.AnnouncementModeInherit {
+		t.Fatalf("默认公告来源应为 inherit, got %q", site.AnnouncementMode)
+	}
+
+	ownOnly := model.AnnouncementModeOwnOnly
+	updated, err := repo.UpdateSiteBranding(ctx, 0, site.ID, UpdateSiteBrandingRequest{AnnouncementMode: &ownOnly})
+	if err != nil {
+		t.Fatalf("切换公告来源失败: %v", err)
+	}
+	if updated.AnnouncementMode != model.AnnouncementModeOwnOnly {
+		t.Fatalf("announcement_mode = %q, want own_only", updated.AnnouncementMode)
+	}
+
+	invalid := "whatever"
+	if _, err := repo.UpdateSiteBranding(ctx, 0, site.ID, UpdateSiteBrandingRequest{AnnouncementMode: &invalid}); !errors.Is(err, ErrInvalidAnnouncementMode) {
+		t.Fatalf("非法来源应返回 ErrInvalidAnnouncementMode, got %v", err)
+	}
+
+	// 读侧容错：库里历史非法值按 inherit 返回
+	if err := db.Model(&model.DistributionSite{}).Where("id = ?", site.ID).
+		Update("announcement_mode", "legacy_value").Error; err != nil {
+		t.Fatal(err)
+	}
+	reloaded, err := repo.FindSite(ctx, 0, site.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if reloaded.AnnouncementMode != model.AnnouncementModeInherit {
+		t.Fatalf("非法历史值应回落 inherit, got %q", reloaded.AnnouncementMode)
+	}
+}

backend/internal/modules/distribution/dto.go

@@ -17,6 +17,7 @@ type SiteDTO struct {
 	AWRecycleJSON           string    `json:"aw_recycle_json"`
 	CooperationFeedbackJSON string    `json:"cooperation_feedback_json"`
 	StorefrontTextJSON      string    `json:"storefront_text_json"`
+	AnnouncementMode        string    `json:"announcement_mode"`
 	DefaultSupportGroupID   *uint64   `json:"default_support_group_id,omitempty"`
 	ListingQrcodeURL        string    `json:"listing_qrcode_url"`
 	ReceiveRatioDelta       float64   `json:"receive_ratio_delta"`
@@ -431,7 +432,51 @@ type UpdateSiteBrandingRequest struct {
 	AWRecycleJSON           *string `json:"aw_recycle_json"`
 	CooperationFeedbackJSON *string `json:"cooperation_feedback_json"`
 	StorefrontTextJSON      *string `json:"storefront_text_json"`
-	ListingQrcodeURL        *string `json:"listing_qrcode_url"`
+	// AnnouncementMode 公告中心来源：inherit（主站+本站）/ own_only（仅本站）。
+	AnnouncementMode *string `json:"announcement_mode"`
+	ListingQrcodeURL *string `json:"listing_qrcode_url"`
+}
+
+// SiteAnnouncementDTO 分站公告（站长自助维护）。
+type SiteAnnouncementDTO struct {
+	ID                 uint64     `json:"id"`
+	DistributionSiteID uint64     `json:"distribution_site_id"`
+	Title              string     `json:"title"`
+	Content            string     `json:"content"`
+	Category           string     `json:"category"`
+	Priority           int        `json:"priority"`
+	IsPinned           bool       `json:"is_pinned"`
+	IsImportant        bool       `json:"is_important"`
+	ViewCount          int        `json:"view_count"`
+	Status             string     `json:"status"`
+	PublishedAt        *time.Time `json:"published_at"`
+	CreatedAt          time.Time  `json:"created_at"`
+	UpdatedAt          time.Time  `json:"updated_at"`
+}
+
+type SiteAnnouncementPage struct {
+	Items    []SiteAnnouncementDTO `json:"items"`
+	Total    int64                 `json:"total"`
+	Page     int                   `json:"page"`
+	PageSize int                   `json:"page_size"`
+}
+
+type CreateSiteAnnouncementRequest struct {
+	Title       string `json:"title" binding:"required,max=255"`
+	Content     string `json:"content" binding:"required"`
+	Category    string `json:"category" binding:"omitempty,oneof=notice tutorial rule faq"`
+	Priority    int    `json:"priority"`
+	IsPinned    bool   `json:"is_pinned"`
+	IsImportant bool   `json:"is_important"`
+}
+
+type UpdateSiteAnnouncementRequest struct {
+	Title       string `json:"title" binding:"max=255"`
+	Content     string `json:"content"`
+	Category    string `json:"category" binding:"omitempty,oneof=notice tutorial rule faq"`
+	Priority    int    `json:"priority"`
+	IsPinned    bool   `json:"is_pinned"`
+	IsImportant bool   `json:"is_important"`
 }
 
 // 自主加价 DTO：增加该站「1 元兑换哈夫币」比例，不是人民币。

backend/internal/modules/distribution/handler.go

@@ -642,6 +642,131 @@ func (h *Handler) resolveSiteID(c *gin.Context) (uint64, error) {
 	return h.service.ScopeSiteID(c.Request.Context(), adminID, requested)
 }
 
+// 分站公告中心（站长自助维护本站公告）。站点由 ?site_id= 解析并校验访问权。
+func (h *Handler) ListSiteAnnouncements(c *gin.Context) {
+	siteID, adminID, ok := h.resolveAnnouncementSite(c)
+	if !ok {
+		return
+	}
+	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
+	resp, err := h.service.ListSiteAnnouncements(c.Request.Context(), adminID, siteID, c.Query("status"), page, pageSize)
+	if err != nil {
+		writeError(c, err)
+		return
+	}
+	response.OK(c, resp)
+}
+
+func (h *Handler) CreateSiteAnnouncement(c *gin.Context) {
+	siteID, adminID, ok := h.resolveAnnouncementSite(c)
+	if !ok {
+		return
+	}
+	var req CreateSiteAnnouncementRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "公告参数格式不正确")
+		return
+	}
+	dto, err := h.service.CreateSiteAnnouncement(c.Request.Context(), adminID, siteID, req)
+	if err != nil {
+		writeError(c, err)
+		return
+	}
+	response.Created(c, dto)
+}
+
+func (h *Handler) UpdateSiteAnnouncement(c *gin.Context) {
+	siteID, adminID, ok := h.resolveAnnouncementSite(c)
+	if !ok {
+		return
+	}
+	id, ok := parseSiteAnnouncementID(c)
+	if !ok {
+		return
+	}
+	var req UpdateSiteAnnouncementRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "公告参数格式不正确")
+		return
+	}
+	dto, err := h.service.UpdateSiteAnnouncement(c.Request.Context(), adminID, siteID, id, req)
+	if err != nil {
+		writeError(c, err)
+		return
+	}
+	response.OK(c, dto)
+}
+
+func (h *Handler) PublishSiteAnnouncement(c *gin.Context) {
+	h.updateSiteAnnouncementStatus(c, "publish")
+}
+func (h *Handler) ArchiveSiteAnnouncement(c *gin.Context) {
+	h.updateSiteAnnouncementStatus(c, "archive")
+}
+func (h *Handler) UnarchiveSiteAnnouncement(c *gin.Context) {
+	h.updateSiteAnnouncementStatus(c, "unarchive")
+}
+
+func (h *Handler) updateSiteAnnouncementStatus(c *gin.Context, action string) {
+	siteID, adminID, ok := h.resolveAnnouncementSite(c)
+	if !ok {
+		return
+	}
+	id, ok := parseSiteAnnouncementID(c)
+	if !ok {
+		return
+	}
+	dto, err := h.service.UpdateSiteAnnouncementStatus(c.Request.Context(), adminID, siteID, id, action)
+	if err != nil {
+		writeError(c, err)
+		return
+	}
+	response.OK(c, dto)
+}
+
+func (h *Handler) DeleteSiteAnnouncement(c *gin.Context) {
+	siteID, adminID, ok := h.resolveAnnouncementSite(c)
+	if !ok {
+		return
+	}
+	id, ok := parseSiteAnnouncementID(c)
+	if !ok {
+		return
+	}
+	if err := h.service.DeleteSiteAnnouncement(c.Request.Context(), adminID, siteID, id); err != nil {
+		writeError(c, err)
+		return
+	}
+	response.OK(c, gin.H{"deleted": true})
+}
+
+// resolveAnnouncementSite 解析公告所属站点：公告路由的 :id 是公告 ID，
+// 因此站点只能来自 ?site_id=（不能复用会优先读 :id 的 resolveSiteID）。
+func (h *Handler) resolveAnnouncementSite(c *gin.Context) (uint64, uint64, bool) {
+	adminID, _ := currentAdminID(c)
+	requested := uint64(parseQueryUint(c, "site_id"))
+	siteID, err := h.service.ScopeSiteID(c.Request.Context(), adminID, requested)
+	if err != nil {
+		writeError(c, err)
+		return 0, 0, false
+	}
+	if siteID == 0 {
+		response.BadRequest(c, "未指定分销站点")
+		return 0, 0, false
+	}
+	return siteID, adminID, true
+}
+
+func parseSiteAnnouncementID(c *gin.Context) (uint64, bool) {
+	id, err := strconv.ParseUint(c.Param("id"), 10, 64)
+	if err != nil || id == 0 {
+		response.BadRequest(c, "公告ID不正确")
+		return 0, false
+	}
+	return id, true
+}
+
 func (h *Handler) UpdateSiteBranding(c *gin.Context) {
 	siteID, err := h.resolveSiteID(c)
 	if err != nil {

backend/internal/modules/distribution/repository.go

@@ -52,6 +52,8 @@ var (
 	ErrInvalidSettlementHold     = errors.New("settlement hold days must be between 0 and 365")
 	ErrBatchNotCancellable       = errors.New("distribution settlement batch cannot be cancelled")
 	ErrSettlementBatchStale      = errors.New("distribution settlement batch stale")
+	ErrAnnouncementNotFound      = errors.New("distribution site announcement not found")
+	ErrInvalidAnnouncementMode   = errors.New("invalid announcement mode")
 )
 
 var settlementReadyOrderStatuses = []string{"completed", "closed"}
@@ -888,6 +890,7 @@ func siteDTO(row model.DistributionSite) SiteDTO {
 		AWRecycleJSON:           row.AWRecycleJSON,
 		CooperationFeedbackJSON: row.CooperationFeedbackJSON,
 		StorefrontTextJSON:      row.StorefrontTextJSON,
+		AnnouncementMode:        normalizeAnnouncementModeOrInherit(row.AnnouncementMode),
 		CreatedAt:               row.CreatedAt,
 		UpdatedAt:               row.UpdatedAt,
 	}
@@ -2750,6 +2753,14 @@ func (r *Repository) UpdateSiteBranding(ctx context.Context, adminID, siteID uin
 		site.StorefrontTextJSON = strings.TrimSpace(*req.StorefrontTextJSON)
 		updates["storefront_text_json"] = site.StorefrontTextJSON
 	}
+	if req.AnnouncementMode != nil {
+		mode, err := normalizeAnnouncementMode(*req.AnnouncementMode)
+		if err != nil {
+			return nil, err
+		}
+		site.AnnouncementMode = mode
+		updates["announcement_mode"] = mode
+	}
 	if req.ListingQrcodeURL != nil {
 		site.ListingQrcodeURL = strings.TrimSpace(*req.ListingQrcodeURL)
 		updates["listing_qrcode_url"] = site.ListingQrcodeURL

backend/internal/modules/distribution/service.go

@@ -313,6 +313,41 @@ func (s *Service) BatchUpdateAccountDisplay(ctx context.Context, adminID, siteID
 	return s.repo.BatchUpdateAccountDisplay(ctx, adminID, siteID, req)
 }
 
+func (s *Service) ListSiteAnnouncements(ctx context.Context, adminID, siteID uint64, status string, page, pageSize int) (*SiteAnnouncementPage, error) {
+	if err := s.available(); err != nil {
+		return nil, err
+	}
+	return s.repo.ListSiteAnnouncements(ctx, adminID, siteID, status, page, pageSize)
+}
+
+func (s *Service) CreateSiteAnnouncement(ctx context.Context, adminID, siteID uint64, req CreateSiteAnnouncementRequest) (*SiteAnnouncementDTO, error) {
+	if err := s.available(); err != nil {
+		return nil, err
+	}
+	return s.repo.CreateSiteAnnouncement(ctx, adminID, siteID, req)
+}
+
+func (s *Service) UpdateSiteAnnouncement(ctx context.Context, adminID, siteID, id uint64, req UpdateSiteAnnouncementRequest) (*SiteAnnouncementDTO, error) {
+	if err := s.available(); err != nil {
+		return nil, err
+	}
+	return s.repo.UpdateSiteAnnouncement(ctx, adminID, siteID, id, req)
+}
+
+func (s *Service) UpdateSiteAnnouncementStatus(ctx context.Context, adminID, siteID, id uint64, action string) (*SiteAnnouncementDTO, error) {
+	if err := s.available(); err != nil {
+		return nil, err
+	}
+	return s.repo.UpdateSiteAnnouncementStatus(ctx, adminID, siteID, id, action)
+}
+
+func (s *Service) DeleteSiteAnnouncement(ctx context.Context, adminID, siteID, id uint64) error {
+	if err := s.available(); err != nil {
+		return err
+	}
+	return s.repo.DeleteSiteAnnouncement(ctx, adminID, siteID, id)
+}
+
 func (s *Service) ListReceivedListings(ctx context.Context, adminID, siteID uint64, q ReceivedListingQuery) (*ReceivedListingPage, error) {
 	if err := s.available(); err != nil {
 		return nil, err

backend/internal/modules/distribution/site_crud_test.go

@@ -3,8 +3,8 @@ package distribution
 import (
 	"testing"
 
-	"hfb_sys/backend/internal/model"
 	"golang.org/x/crypto/bcrypt"
+	"hfb_sys/backend/internal/model"
 )
 
 func TestSiteCRUD_UpdateSiteAndDomainUniqueness(t *testing.T) {